Self-priming pump



Dec. 25, 1945. R. D. CAMPBELL SELF-lRIMING PUMP Filed May 14, 1943Patented Dec. 25, 1945 UNITED STATE-s PATENT OFI-ice SELF-PRIDHNG PUMP Imenare n. campbell. wauwau, wir., mignor to Allis-Chalmers ManufacturingCompany, Milwaukee, Wis., a corporation o! Delaware Application May 14,1943, Serial No. 486,939

15 Claims. (Cl. 103-113) This invention relates to improvements inselfpriming pumps and particularly to self-priming centrifugal pumps inwhich recirculation of the water for priming is automatically cuto whenthe discharge conditions oi the pump change as a result oi completion ofthe priming action.

Centrifugal pumps are impositivo displacement machines and cannotdischarge liquids until all ofthe gases have been removed from thesuction line and the pump casing. Such gas removal or priming may beaccomplished by completely illling the suction line and the pump casingfrom a source oi liquid at a higher elevation, by removing the gases bythe use of a separate evacuating pump or by causing entrainment ci thegases by liquid recirculating within the pump and then releasing theentrained gases to the discharge line thus making the pump self-priming.Seli-priming pumps, after completion of the self-priming action, shouldof course be as eective as other centrifugal pumps both as to the depthfrom which liquids can be lifted and as to the eiliciency with whichliquids are discharged. It is desirable that such self-priming pumps beoperative at all times after the initial starting action regardless ofhowi frequently the reservoir from which the liquid is obtained, iscompletely emptied. Thel priming action should be as rapid and smooth aspossible to avoid the occurrence of power losses and the production ofintermittent stresses in the pump structure.

The recirculating control valve should be 'unaffected by variations inthe suction liit during the priming action and is preferably operativeonly in response to the discharge velocity of the pumped liquid. Thevalve should close as soon as the need for recirculation of liquid hasceasedy and the valve should be so designed as to be insensitive tooperating conditions and not subject to misadjustments during use. It istherefore an object of the present invention to provide an improvedself-priming centrifugal pump in which water is recirculated onlyaiiected by the varying suction lift or discharge head oi' the pumpduring the priming action.

Another object of the invention is to provide an improved self-primingcentrifugal pump in which the wateriiowing through the recirculatingvalve -is continuously and immediately picked up by the pump impeller,thus preventing an intermittent priming action producing intermittentstresses in the pump structure.

Objects and advantages other than those above set forth will be apparentfrom the following description when read in connection with theaccompanying drawing in which:

Fig. 1. is a vertical sectional view taken on the line I-I oi Fig. ,2through the axis of both the valve chamber and the pump to show thevalve structure and the relation of the valve controlled ow to theowpassing through the pump;

Fig. 2 is a top plan view of the entire self-priming pump structure; vFig. 3 is an elevation taken from the inlet or suction side of the pumpwith a portion of the valve chamber wall broken away and with therecirculation control valve shown in vertical section on a plane takencentrally therethrough to illustrate the relation of the valve with theother portions of the structure; and

liig. 4 is a horizontal section taken on the plane of the line IV-IV ofFig. 1 to show the relation oi the port controlled by the recirculatingvalve with the inlet of .the pump as Well as to show the shape andlocation of the discharge passage from the pump and leading through thevalve.

It will be understood, of course, that the pump may also be placed withthe shaft in vertical posif tion or at any other angle to thehorizontal.

Referring more particularly to the drawing by A type, it beingunderstood that any known type of impeller may be used. The pumpimpeller is mounted on a shaft 8 to which power is to be applied by anyknown driving means (not shown) and the joint between the stationarycasing and the rotating hub of the impeller is closed by a packing gland9. The inlet through the pump v casing 6 into the eye of the impeller isdesignated at Il and the discharge passage from the usual volute portionof the casing 6 is shown at l2.

Y A chamber generally designated at I3 is mounted adjacent or,preferably, formed integral with, a portion of the pump casing 6 in suchmanner as to form one side thereof with the pump inlet ii formed in thewall portion between the pump casing itself and the chamber I3, asshown. The casing outlet and discharge conduit I2 `extend outwardly fromthe volute portion of the casing and upwardly to open into the chamberI3 at one side thereof. Water is admitted to the intake portion of thechamber I3 by way of a suction pipe I4 provided with s, check valve I!and the water thus admitted flows through an inlet' conduit portiondefined by walls I6 formed on the inner wall of the chamber and throughthe inlet II into` the impeller 1, and water is discharged from the pumpthrough the discharge outlet I2' and the other side of the chamber I3into a discharge pipe I1. The chamber I3 is provided with a cover I8having a removable plug I3 by way of which the chamber may be initiallyfilled with water, it being understood that such filling is requiredonly the first time the pump is started. It will oe seen that the inletconduit formed by walls I6 provides a complete and separate passagewayon one side of chamber I3 from the inlet pipe I4 to the pump casinginlet II and is wholly separated from the discharge -space within thechamber except for controlled ports to be described.

The pump outlet I2 opens into a pocket formed in the bottom of thedischarge space of the chamber I3 to provide a receptacle for a valvehousing having a cylindrical body portion 20 with internal flanges 2|and 22 and an external ilange 23. A spider comprising a central ring 23and four arms 21 is mounted on flange 22 ofthe valve housing and acentrally apertured screen 28 is mounted on the flange 23 and extendsover the spider. The valve housing encloses and guides a movable valvebody formed with a hollow cylindrical bottom portion 3| having an ex'ternal flange 32 and with an internal flange 33 from which extends, atright angles thereto, a smaller hollow cylindrical upper valve portion34 extending above the valve housing. into the chamber I3. The lowervalve ange 32 fits into the valve housing and the lower cylindricalvalve portion 3| fits into the opening formed by th'e valve housingflange 2| for the purpose of aiding in guiding the valve in its verticalmovement. The upper valve extension or nozzle 34 also fits closely inthe ring 26 of the spider to guide the vertical movement of the uppervalve extension 34. The fit of housing flange 2| and lower cylindricalvalve portion 3| in the valve housing also increases resistance toleakage about the periphery of such flange thereby preventing air flowback to the suction space with consequent increase in priming timere'quired and loss of priming efficiency due to only partially eectivedischarge.

The spaces about the spider arms 21 provide passages through which watermay flow from the chamber I3 between the flange 22 of the valve housingand the valve body extension 34 and through a port 36 in the valvehousingr 1ocated between flanges 2| and 22 and adjacent the impellerinlet II. The valve body is Joined to a helical spring 31 under tensionand having one end thereof fastened to a plate 38 on which the valvehousing is seated and retained in the pocket provided therefor. Thevertical movements of the valve are also, at least in part, guided bythe spring 31. Due to guiding of the valve by the various flanges, thespider and the spring, it is impossible for the valve body to move froma vertical position suiilciently to cause jamming of the valve under anycircumstances.

One wall I6 defining the suction conduit within the chamber I3 isprovided with an aperture 4I asomo connecting the suction space k42 ofthe chamber I3 with' the discharge space 43 thereof and the aperture maybe closed by a ball check valve 44. If the check valve Il should notseat tightly and allow water to syphon back into the suction pipe -valveIl' is closed and the recirculating control valve 3| to 34, inclusive,is drawn downwardly by the spring 31 into the position shown in Figs. 1and 3 of the drawing. If the pump is to be started, the space 43 of thechamber I3 must first be filled with water through the' opening which isclosed by the plug I 3. The pump can then be started and water from thespace 43 is drawn through a priming or recirculatins path designated a,between the valve housing internal flange 22 and the valve cylindricalupper portion 34 to iiow through theport 36 into the inlet II of theimpeller 1. Water is, discharged from the impeller through the outlet I2and passes up through the valve 3I 34 into the space 43 of the chamberI3 in which air separates from the water and passes out through thedischarge pipe I1. Separation of gas from liquid in space 43 is promotedby valve extension 34 which acts as a nozzle to discharge the gas liquidmixture with sumcient force to carry the gas bubbles beyondrecirculation path a. Entrainment of the gas bubbles-.is

minimized by the screen plate 23 mounted on the valve housing andfitting relatively closely about I' the valve extension 34 thusblockingreturn of gas bubbles of any size through the recirculation path. Theabove recirculation of water through' the path a continues until all ofthe air is drawn l out of the suction conduit space 42 and the sucutesat a speed of 1750 R. P. M.

During recirculation of a gas and water mixture in the path a the spring31 holds the valve 3I-34 substantially in the position shown with therecirculation or priming ports at least pal'- tially open. However, assoon as the pump is discharging only gas free liquid, the velocity ofthe discharge acts on the inner surface of the valve nange 33 and raisesthe valve 3I-34 against the tension of the spring 31 until the flanges32 and 33 of the valve body are seated on the flanges 2| and 22 of thevalve housing thereby closing of! the recirculation path a. Expressed indifferent language, lifting of the valve results from th'e diierentialpressure due to high suction lift and zero or lowy discharge or positivestatic head thus producing an increase in velocity through the valve. Asthe valve lifts the velocity decreases to a constant rate and hence thevalve can operate under varying suction and discharge heads. Uponclosure of valve 3|-34, water flows through the normal pumping path b,that is through the suction pipe I4, the suction conduit space 42, theimpeller inlet II and is forced by the impeller 1 into the voluteportion of the casing 6 from whichthe water flows through the casingoutlet I2, the valve 3I-34, vthe discharge asomo@ The present structurehas been found to liave a number of critical characteristics. Thus therecirculation port 36 must be located adjacent to and in line with theimpeller inlet Il to allow the impeller 'I to pick up water immediatelyandcontinuously. Location of the port 36 as shown allows the jet ofwater issuing therefrom to en train air in the suction space 42continuously and to carry it immediately into the impeller. There is norelease of such entrained air and there is no loss of time or power dueto unnecessary turbulence in the suction space 42. If the recirculationport is located in any other position. the suction space 42 must beiilled up to the level at which more than onefhalf of the pump inlet IIis under water before the impeller will pick up the water. The impellerthen picks up charges of water interspersed with a quantity of air anddelivers the charges of water as solid masses to the recirculation patha. Such so-called slugging imposes intermittent stresses on the entirepump structure and its operating means and momentarily causes the valve3i-38 to lift. As

l .soon as each slug passes into the discharge space @3, the stresses onthe pump are relieved and the valve 3i-34 is retracted byl the spring 3lthus causing hammering of the valve. Under such conditions the pumpcannot prime smoothly and 3i--3d. Such action would vary as the suctionlift varies and would vary the action of the valve. But if thecross-sectional area of the port 38 and the other controlled portions ofthe recirculation path a are made smaller than the cross-sectional areaof the valve chamber as dened by iianges 2i, 22 and body 20 of the valvehousing, a' pressure is built up in the valve chamber and neutralizesthe effect of th'e variable suction lift on the valve. The valve 3i--34is therefore actuated only responsive to the velocity of ilow throughthe valve and a single spring 31 satisfactorily controls valve movementover the entire range of the suction lift. Further,v the smaller portarea increases the gas liquid mixture velocity beyond the point at whichth'e gas may separate and also limits the ow to the impeller to :preventiiooding thereof.

'The stroke of the valve 3l34 between closed and wide open position,`that is the space between the' flanges of the valve housing and thevalve, should be kept to relatively close limits. Ii the valve travelsless than inch the spring tension must be increased beyond the tenpounds found satisfactory 'in-practice and the valve then slams open andshut. And an increase in the valve stroke beyond 3/4 inch makes itnecessary to increase iiange area 33 to such an extent that muchturbulence is caused and eiciency is lost in ow through the valve. Suchstroke limitation also prevents the valve from moving other than in avertical direction and becoming jammed.

The nozzle portion 34 of the recirculating valve must extend above thebottom oi.' the discharge space 43 for a suilicient distance to allowcomplete separation of the air from the recirculating water outside oithe recirculation path a and thus permit escape of such entrained air upthrough the discharge pipe I'l. Ii' the valve is made too short theentrained air is recirculated with the water and no priming action takesplace.

A ratio, dependent on the tension of the spring 31, z nust be maintainedbetween the area of the inner surface of the iiange 33 of therecirculation contro1 valve, on which the velocity pressure of the wateracts to shut oil the valve, and the area oi' the portion 34 of the valvethrough which the pump discharge must flow. The ratio, having a givenspring tension, must be such that the valve is closed as soon as thevolume ci.' water pumped is greater than th'e volume oi' the water whichcan return through the recirculation port 38.

And the discharge head is related to the area of the bypass port 36. Forhigher discharge heads, the port must be made smaller because a greaterquantify of water flows through th'e recirculation path, increasing thevelocity of the air-water mixture beyond the point at which the air isreadily released. The velocity must be kept down either by decreasingthe port area or increasing the volume of space 43.

Although but one embodiment of the present invention has beenillustrated and described, it

` will be apparent to those skilled in the art that various changes andmodifications may be made therein without departing from the spirit oithe invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on said casing and divided into asuction space connected with the inlet ofsaid impeller and separatedfrom a, discharge space receiving the discharge from said. casing, ahollow valvel member defining a passage through which the entiredischarge from said casing is conducted to the discharge'space of saidchamber under all conditions of pump operation. said valve member beingslidably mounted to control a port connecting the suction and dischargespaces in said chamber, and spring means cooperating with said valvemember to maintain communication between said suction and dischargespaces through' said port when said pump is inoperative and duringpriming thereof.

2. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on said casing and divided into asuction space connected with the inlet of said impeller and separatedfrom a discharge space receiving the discharge from said casing, a bailcheck valve controlling an aperture in the wall separating the suctionand discharge spaces in said chamber to break any syphon action in thesuction space, and a valve member conducting the entire discharge fromsaid casing into the discharge space of said chamber and controlling aport connecting the suction and discharge spaces in said chamber.

3. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on said casing and divided into asuction space connected with the inlet of said impeller and separatedfrom a discharge space receiving the discharge from said casing, a valvehousing mounted in the discharge space of said chamber and having a portconnecting the suction and discharge spaces in said chamber, and ahollow valve element mounted for sliding movevided into a suction spaceconnected with the iny iet of said impeller and separated from adischarge space receiving the discharge from said casing, a valvehousing mounted in the discharge space of said chamber and having a portconnecting the suction and discharge spaces in said chamber, said portbeing adjacent to and in line with the inlet of said impeller, and ahollow valve element mounted for sliding movement in said valve housingfor conducting therethrough the entire discharge from said casing intothe disy charge space of said chamber and controlling the recirculationof liquid between the spaces through said port.

5. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a

chamber mounted adjacent said casing and divided into a suction spaceconnected with the inlet of said impeller and separated from a dischargespace receiving the discharge from said casing, a valve housing mountedin the discharge space of said chamber, said housing having a pluralityof internal flanges and a port between the flanges connecting thesuction and discharge spaces in said chamber, and a valve mountedV insaid housing for conducting the entire discharge from said casing intothe discharge space of said chamber, said valve having flanges seatingon the flanges of said housing to control recirculation of liquidbetween the spaces through the port.

6. In a self-priming centrifugal pump, a cas-V ing, an impellerrotatable within said casing, a chamber mounted adjacent said casing anddivided into a suction space connected with the inlet of said impellerand separated from a discharge space receiving the discharge from saidcasing, a valve housing mounted in the discharge space of said chamberand having a port connecting the suction and discharge spaces in saidchamber, and 'a valve mounted in said valve h'ousing for conducting theentire discharge from said casing into the discharge space of saidchamber and controlling the recirculation of liquid'between the spacesthrough the port, said housing and said valve having a plurality ofinterengaging flanges with the upper of said valve flangesv having anarea greater than the area of the discharge passage through said valveto cause closing of said valve responsive to the velocity of thedischarge therethrough.

7. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on said casing and divided into asuction space connected with the inlet of said impeller and separatedfrom a discharge space receiving the discharge from said casing, a valvehousing mounted in the bottom of the discharge space of said chamber andhaving a port connecting the suction and discharge spaces in saidlchamber, and a valve mounted in said chamber and controlling therecirculation o!v liquid between' the spaces through the port. saidhousing having a plurality of nanges with the upper one of the flangeshaving extensions therefrom fitting closely about said valve and saidvalve having a plurality of flanges with the lower one of the flangesfitting closely into said housing to guide movement of said valve.

8. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on said casing and divided into asuction space connected with the inlet of said impeller and separatedfrom a discharge space receiving the discharge from said casing, a valvehousing mounted in the bottom of the discharge space of said chamber andhaving a port connecting the suction and discharge spaces in saidchamber, and a valve mounted in said valve housing for conducting theentire discharge from said casing into the discharge space of saidchamber and controlling the recirculation of liquid between the spacesthrough the port, -said housing and said valve having a plurality offlanges, the movement of said valve being limited by engagement of theflanges thereof with the'flanges -of said valve housing.

9. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on'said casing and divided into asuction space connected with the inlet of said impeller and separatedfrom a discharge space receiving the discharge from said casing, a valvehousing mounted in the bottom of the discharge space of said chamber andhaving a port connecting the suction and discharge spaces in saidchamber, and a valve mounted in said valve housing for conducting theentire discharge from said casing into the discharge space of saidchamber and controlling the recirculation of liquid between the spacesthrough the port, said housing and said valve having a plurality ofinterengaging flanges, the lower one of said housing flanges fittingclosely about said valve and the lower one of said valve flanges fittingclosely in said housing to reduce leakage from the discharge space tothe suction space of said chamber.

10. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a chamber mounted on said casing and divided into asuction space connected with the inlet of said impeller and separatedfrom a discharge space receiving the discharge from said casing, a valvehousing mounted in the bottom of the discharge space of said chamber andhaving a port connecting the suction and discharge spaces in saidchamber, a valve mounted in said valve housing for conducting the entiredischarge from said casing into the discharge space of said chamber andcontrolling the recirculation of liquid between the spaces throughtheport, said housing and said valve having a plurality ofinterengaging.

anges with the upper of said valve flanges having an area greater thanthe area of the-discharge passage through said valve to cause closing oisaid valve responsive to the velocity of the discharge therethrough, anda spring joining said housing and said valve to allow closing of saidvalve only at a predetermined velocity.

1l. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a suction and a discharge conduit associated withsaid casing, a hollow valve element defining a passage through which theentire discharge from said casing is conducted to said dischargeconduit-underI all conditions of pump operation, said valve controllinga port connecting said suction conduit with said discharge conduit, andmeans for regulating movement of said valve responsive to the velocityof ow through said valve.

12.. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a suction and a discharge conduit associated withsaid casing, a valve housing mounted in said discharge conduit, saidhousing having a plurality of internal flanges forming a valve chamber,a port connecting said valve chamber with said suction conduit, saidport being of less cross-sectional area than said valve chamber, and avalve mounted in said housing for conducting discharge from said casingto said discharge conduit and controlling said port.

13. ln a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a suction and a discharge conduit associated withsaid casing, valve means controlling an aperture between said dischargeconduit and said suction conduit to break any Siphon action in saidsuction conduit, and a valve for conducting the discharge from saidcasing to said discharge conduit, said valve controlling a portconnecting said suction conduit with said discharge conduit.

14. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a suction and a discharge conduit associated withsaid casing, a valve housing mounted in said dis-- charge conduit, saidhousing having a plurality of internal flanges and a port between saidflanges connecting said suction and discharge conduits, and a valvemounted in said housing for conducting the entire discharge from saidcasing into said discharge conduit, said valve having flanges seating onthe flanges of rsaid housing to control recirculation of liquid betweensaid conduits through said port.

15. In a self-priming centrifugal pump, a casing, an impeller rotatablewithin said casing, a suction and a discharge conduit associated withsaid casing, a port connecting said suction and Adischarge conduits,said port being adjacent to and in line with the inlet of said impeller,and an annularvalve element having-a tubular portion dening a passagethrough which the entire discharge from` said casing is conducted tosaid discharge conduit under all conditions -oil pump operation, saidvalve element being exposed to pressure of uid discharged from said pumpand being actuated in responseto velocity of flow through said valveelement for controlling said port.

RECHARD D. CMPBELL.

